1. Field of the Invention
The present invention relates to a hybrid vehicle (referred to as an HV) having a plurality of components such as an engine, a motor and the like, and more particularly is directed to an apparatus for promoting warm-up of the engine while cooling other components.
2. Description of the Related Arts
In a hybrid vehicle (HV) there are mounted an engine and a motor which are intended to cooperatively generate power for driving the vehicle. Among several types of HV's, there is a type called series HV (referred to as SHV hereinbelow) in which its engine, generator and motor are connected in series. In the SHV, the engine drives the generator whose output power in turn drives the motor. In the case of using a D. C. generator as the generator, a D. C. output of the generator is converted into an alternating current by means of an inverter prior to supply to the motor. In this case, a rechargeable battery may be connected between the generator and the inverter so as to store the D.C. output of the generator therein and to drive the motor with the aid of the output of the battery. Furthermore, the inverter may be controlled to derive a required output from the motor.
At the time of actuating the engine in such a vehicle, a fuel-air mixture ratio when the engine is cold is set so as to differ from that when the engine is warmed up. That is, while the engine is cold, the ratio of fuel is increased compared with the warmed-up engine. However, if actuating the engine in the cold, a larger amount of harmful materials such as CO, HC, and NO.sub.X which are contained in an exhaust gas may be produced than the engine which has been warmed up. A proper catalyst may be used to eliminate such harmful materials. In the cold, however, the temperature of the catalyst is also low. The catalyst at a relatively lower temperature generally has a poor working efficiency and adversely increases so-called emission as described hereinbefore. In addition, when the temperature of the engine is low, a lubricating oil of the engine also has a higher viscosity. If the viscosity of the lubricating oil is high, the engine itself presents a large frictional resistance, which leads to a poor fuel consumption.
A possible means of solving such problems is disclosed in Japanese Utility Model Publication No. 56-17724 in which an engine vehicle includes a heater used for warming up the engine at the time of cold start. To this end, the heater may be arranged around the engine. In this publication, a battery is provided as a power source of the heater.
Such an additional heater is applicable to the HV as well. In this case, as the HV has already been provided with the battery for the drive of the motor as described above, it may be natural to use this battery as the power source of the heater. Nevertheless, if the motor drive and the energization of the heater are carried out by the same battery, there may arise another disadvantage that the power of the battery is partly consumed due to the energization of the heater, which shortens the traveling distance per unit charge of battery.